1. Field of the Invention
The present invention relates to lens driving devices, and particularly to a lens driving device with a shaking correction function used for driving a camera of a mobile phone to carry out auto focus and correcting shaking occurring on the camera.
2. Description of Related Art
Lens driving devices with a shaking correction function use an auto focus function to carry out auto focus, and use a shaking correction function to swing the lens in directions forming a right angle with an optical axis of the lens correspondingly when a shake is occurred in shooting so as to inhibit an image formed on an image sensor from being fuzzy. For example, Japanese patent application with an application publication number of JP2013-24938A and a publication date of Feb. 4, 2013 (by taking the application as the priority, US patent publication Nos. US20130016427A1 and US20150226978A1 with publication dates of Jan. 17, 2013 and Aug. 13, 2015) provides a lens driving device 50 with a shaking correction function. A focusing unit is suspended and supported to swing in directions forming the right angle with the optical axis by using linear spring members extending along the direction of the optical axis, and the focusing unit swings by operating a hand shake correcting unit so as to inhibit the image from being fuzzy.
As shown in FIG. 5A to FIG. 5C, the lens driving device 50 with the shaking correction function is illustrated. Particularly, FIG. 5A is a perspective view of the lens driving device 50 with the shaking correction function, FIG. 5B is an explosive view of the lens driving device 50 with the shaking correction function, and FIG. 5C is a perspective view of main parts of the lens driving device 50 with the shaking correction function. Hereon, a direction of an optical axis of the unshown lens is set to be a Z (Z-axis) direction, and two directions which form right angles with the Z axis and vertical to each other are set to be a P (P axis) direction and a Q (Q axis) direction respectively.
As shown in FIG. 5A, the lens driving device 50 with the shaking correction function is accommodated in a shielding box body 65, and is integrally formed in a cuboid shape. A circular ring-shaped opening is formed in the central part of the screening box body 65 in the Z-axis direction, and an unshown lens is maintained by a lens support 53 in the central part.
The lens driving device 50 is composed of a focusing unit 51 and a hand shake correcting unit 52.
The focusing unit 51 is provided with a lens support 53, a focus coil 54A, magnets 55A and a magnet support 56, a suspension supporting mechanism composed of plate-like spring members 57 and a spacer 58. The hand shake correcting unit 52 is provided with correction coils 59A, a wiring substrate 62A, a connecting substrate 62B, a swing supporting mechanism 60 composed of the linear spring members, Hall elements 61 for position detection and a base station 63.
The lens support 53 is a cylindrical member with an opening in the Z-axis direction, and is used for maintaining the lens on the inner peripheral side. The focus coil 54A is wound into a square ring shape along an outer diameter side of the lens support 53. The magnetic pole faces of the total four magnets 55a form a cuboid shape, face a P-axis direction and a Q-axis direction, and are arranged on an outer diameter side of the focus coil 54A at 90-degree intervals around an axis parallel to the Z axis. The magnets 55A are separated from and arranged opposite to the focus coil 54A at intervals along the P-axis direction and the Q-axis direction. Moreover, the magnets 55A are maintained on the frame edge part 56A of the square frame-shaped magnet support 56.
The suspension supporting mechanism 57 is composed of a front side spring member 57A and a rear side spring member 57B. The inner peripheral parts of the front side spring member 57A and the rear side spring member 57B are connected with the +Z side end surface and the −Z side end surface of the lens support 53 respectively. Moreover, the outer peripheral part of the front side spring member 57 is connected with the +Z side end surface of the magnet support 56. The outer peripheral part of the rear side spring member 57B, together with the spacer 58 on the outer peripheral part, is connected to the −Z side end surface of the magnet support 56. As a result, the front side spring member 57A and the rear side spring member 57 B are used for suspending and supporting the lens support 53 to move in the Z-axis direction.
When the focus coil 54A of the focusing unit 51 is electrified, Lorentz force in the Z-axis direction is generated, and the lens support 53 moves in the Z-axis direction based on the Lorentz force.
The connecting substrate 62B connected with an external control circuit is mounted on the +Z side surface of the plate-like base station 63 with an opening in the central part in the Z-axis direction. The wiring substrate 62A is mounted on the +Z side surface of the connecting substrate 62B. An electric power supply circuit is formed on the wiring substrate 62A, and the upper part of the electric power supply circuit is connected with the correction coils 59A.
The correction coils 59A include P side correction coils 59AP which are wound around axises parallel to the Z axis and are assembled on the −P side and the +P side of the wiring substrate 62A respectively and Q side correction coils 59AQ which are wound around axises parallel to the Z axis and are assembled on the −Q side and the +Q side of the wiring substrate 62A respectively. The correction coils 59A are separated from and arranged opposite to the −Z side surfaces of the magnets at intervals along the Z-axis direction.
The swing supporting mechanism 60 is composed of four linear spring members extending along the Z axis direction. The front side end part 60a of each spring member is connected with the front side spring member 57A, and the rear side end part 60b of each spring member is connected with the base station 63. The swing supporting mechanism 60 is used for supporting the focusing unit 51 to swing in the P-axis direction and the Q-axis direction.
As shown in FIG. 5C, the Hall elements 61 for position detection are composed of a Hall element 61P on the side of the P axis and a Hall element 61Q on the side of the Q axis. The Hall element 61P assembled on the −Z side of the correction coils 59AP is fixed on the base station 63, and is separated from and arranged opposite to the −Z side surfaces of the magnets 55A at intervals via the P side correction coils 59AP along the Z-axis direction. The Hall element 61Q assembled on the −Z side of the correction coils 59AQ is fixed on the base station 63, and is separated from and arranged opposite to the −Z side surfaces of the magnets 55A at intervals via the Q side correction coils 59AQ along the Z-axis direction.
The Hall elements 61P, 61Q are all used for detecting magnetic induction intensity in the Z-axis direction generated by the oppositely arranged magnets 55A. As a result, the change of magnetic induction intensity generated along with the swing of the oppositely arranged magnets 55A in the P-axis direction is detected by the Hall element 61P. Moreover, the change of magnetic induction intensity generated along with the swing of the oppositely arranged magnets 55A in the Q-axis direction is detected by the Hall element 61Q. Thus, the Hall element 61P can obtain the swinging position of the magnet support 56 along the P-axis direction, and the Hall element 61Q can obtain the swinging position of the magnet support 56 along the Q-axis direction.
And then, when the P side correction coils 59AP of the hand shake correcting unit 52 are electrified, the P side correction coils 59AP generate the Lorentz force in the P-axis direction, and the magnets 55A generate counteracting force, so that the focusing unit 51 swings in the P-axis direction. Moreover, when the Q side correction coils 59AQ are electrified, the Q side correction coils 59AQ generate the Lorentz force in the Q-axis direction, and the magnets 55A generate counteracting force, so that the focusing unit 51 swings in the Q-axis direction.
As a result, when hand shaking is generated during shooting, the P side correction coils 59AP and the Q side correction coils 59AQ are electrified, and the swing amplitude is monitored by the Hall element 61P and the Hall element 61Q, so that hand shake correction is implemented accordingly.
However, as shown in FIG. 5C, the magnets 55A with rectangular cross sections observed from the Z-axis direction are assembled on the outer side of four sides of the square ring-shaped focus coil 54A, namely on the outer side in the P-axis direction and the Q-axis direction, so that the width in the P-axis direction and the width in the Q-axis direction of the lens driving device 50 are increased, and the lens driving device 50 with the shaking correction function is large-sized.
Therefore, as shown in FIG. 6A, the Japanese patent application with the application publication number of JP2014-126668A and the publication date of Jul. 7, 2014 (by taking the application as the priority, US patent application publication No. US2014177056A1 with the publication date of Jun. 26, 2014) discloses another lens driving device with a shaking correction function. FIG. 6A illustrate perspective views of main parts of the lens driving device with the shaking correction function. In the lens driving device, the magnets 55B with isosceles trapezoid-shaped cross sections observed from the Z-axis direction are maintained at the corners of an unshown quadrate magnet support, namely at the corner positions with long distances (in the X-axis direction and the Y-axis direction) so as to avoid an increase of the width in the P-axis direction and the increase of the width in the Q-axis direction. Moreover, in FIG. 6A and FIG. 6B, the X-axis direction is the direction of rotating by 45 degrees around the Z axis from the P-axis direction to the +Q-axis direction, and the Y-axis direction is the direction of rotating by 45 degrees around the Z axis from the Q-axis direction to the −P-axis direction.
The focus coil 54B is wound around the axis parallel to the Z axis along the outer surface of the unshown lens support, and is octagonal ring-shaped. The magnetic pole faces of the magnets 55B face the X-axis direction and the Y-axis direction, and the total four magnets 55B are assembled on the outer diameter side of the focus coil 54B diagonally at 90-degree intervals around the axis parallel to the Z axis. And then, the magnets 55B are separated from and arranged opposite to the focus coil 54B at intervals along the X-axis direction and the Y-axis direction, and are maintained at four corners of the unshown square frame-shaped magnet support.
When the focus coil 54B is electrified, the focus coil 54B generates Lorentz force in the Z-axis direction, so that the unshown lens support moves in the Z-axis direction.
The correction coils 59B include X side correction coils 59BX assembled on the −X side and the +X side and wound around the Z-axis direction respectively, and Y side correction coils 59BY assembled on the −Y side and the +Y side and wound around the Z-axis direction respectively. The correction coils 59B are separated from and arranged opposite to the −Z side surfaces of the magnets 55B at intervals along the Z-axis direction.
When the X side correction coils 59BX are electrified, the X side correction coils 59BX generate the Lorentz force in the X-axis direction, and the magnets 55B generate counteracting force, so that the unshown focusing unit 51 swings in the X-axis direction. Moreover, when the Y side correction coils 59BY are electrified, the Y side correction coils 59BY generate the Lorentz force in the Y-axis direction, and the magnets 55B generate counteracting force, so that the unshown focusing unit 51 swings in the Y-axis direction.
Hereon, magnet 64PP used for position detection and magnetized along the X-axis direction is assembled on the outer side in the +P-axis direction of the focus coil 54B, and the magnet 64PP is fixed on the unshown magnet support. Moreover, the magnet 64PM used for position detection and magnetized in the Y-axis direction is assembled on the outer side in the −P-axis direction of the focus coil 54B, and is fixed on the unshown magnet support.
The Hall elements 61 for position detection are composed of a Hall element 61PP on the +P side and a Hall element 61PM on the −P side. The Hall element 61PP is assembled on the −Z side of the magnet 64PP, and is fixed on the unshown base station. The Hall element 61PM is assembled on the −Z side of the magnet 64PM, and is fixed on the unshown base station.
Thus, the Hall element 61PP is separated from and arranged opposite to the magnet 64PP at an interval along the Z direction, and the Hall element 61PM is separated from and arranged opposite to the magnet 64PM at an interval along the Z direction. Moreover, the Hall element 61PP can detect the components of the Z-axis direction of magnetic induction intensity generated by the magnet 64PP. The Hall element 61PP can detect the components of the Z-axis direction of magnetic induction intensity generated by the magnet 64PM.
And then, the Hall element 61PP detects the change of magnetic induction intensity generated along with the swing of the magnet 64PP in the X-axis direction. The Hall element 61PM detects the change of magnetic induction intensity generated along with the swing of the magnet 64PM in the Y-axis direction.
Thus, the Hall element 61PP can obtain the swinging position of the magnet support along the X-axis direction, and the Hall element 61Q can obtain the swinging position of the magnet support along the Y-axis direction.
As a result, when hand shaking is generated in shooting, the X side correction coils 58BX and the Y side correction coils 59BY are electrified, and the swing amplitude is monitored by the Hall element 61PP and the Hall element 61PM, so that hand shake correction is implemented.
Thus, in the Japanese patent application with the publication number of JP2014-126668, the magnets 55B are configured at opposite corners so as to prevent the width dimensions from being increased, and large size can be avoided. However, in the other aspect, the magnets 64PP, 64PM for position detection need to be mounted, thus the number of components of the lens driving device is increased, the structure becomes complicated and the product cost becomes higher.
In order to solve the above problems, the lens driving device with the shaking correction function as shown in FIG. 6B is provided, the magnets 64PP, 64PM for position detection are not used, and the Hall elements 61X, 61Y are arranged at the back of the magnets 55B in the Z-axis direction and are used in position detection.
Under the condition, the Hall element 61X for position detection is assembled on the −Z side of the correction coils 59BX and is fixed on the unshown base station, and is separated from and arranged opposite to the −Z side surface of the magnets 55B at intervals across the correction coils 59BX along the Z-axis direction. The Hall element 61Y for position detection is assembled on the −Z side of the correction coils 59BY and is fixed on the unshown base station, and is separated from and arranged opposite to the −Z side surface of the magnets 55B at intervals across the correction coils 59BY along the Z-axis direction.
The Hall elements 61X, 61Y are all used for detecting the components of Z-axis direction of magnetic induction intensity generated by the oppositely arranged magnets 55B. Particularly, the Hall element 61X is used for detecting the change of magnetic induction intensity generated along with the swing of the oppositely arranged magnets 55B in the X-axis direction. The Hall element 61X is used for detecting the change of magnetic induction intensity generated along with the swing of the oppositely arranged magnets 55B in the Y-axis direction. Thus, the Hall element 61X can obtain the swinging position of the magnet support along the X-axis direction, and the Hall element 61Y can obtain the swinging position of the magnet support along the Y-axis direction.
Hereon, the Hall elements 61X, 61Y assembled at the back of the Z-axis direction of the correction coils 59B may miss magnetic noise generated along with the electrification of the correction coils 59B so as to generate error position detection signals. In order to inhibit the missing of the magnetic noise, the correction coils 59BX are clamped between the magnets 55B and the Hall elements 61X and the correction coils 59BY are clamped between the magnets 55B and the Hall elements 61Y. The correction coils 59B do not face the middle parts of the Hall elements 61X and the Hall elements 61Y, but each correction coil 58B that corresponding to one of the Hall elements 61X and the Hall elements 61Y is cut into two winding sheets. However, when the correction coils 59B are cut into the winding sheets, the cross amount of magnetic induction lines generated by the magnets 55B and the cut correction coils 59BX, 59BY is reduced, so that the driving force (swinging force) during swinging is reduced.